A teenage drug dealer who carried a knife as "an insurance policy" stabbed one of his customers three times in the middle of a busy town centre, a court has heard.

Deighton Wilson, 17, from Thorton Heath, appeared at Guildford Crown Court today, May 14, to stand trial for wounding with intent to cause grievous bodily harm to Carlos Ferreira on November 27 last year.

A jury of seven men and five women heard how Mr Wilson became involved in an altercation with Mr Ferreira and his friend Dean Price, who he was selling drugs to.

Richard Elliott, prosecuting, said the trio met in Rosebery Park, in Epsom, before travelling to Epsom High Street, where the fight, in which Mr Ferreira was stabbed in his rib, thigh and leg by Mr Wilson, broke out.

He said Mr Wilson claims that he was acting in self-defence as the pair were robbing him of the drugs he intended to sell to them.

Opening the case, Mr Elliott said: "When you run a small business you can get insurance for fire damage and theft and if something goes wrong you can call the police.

"Drug dealers need their own insurance policy. This man has his own insurance policy which is carrying a knife. " He admits he is a drug dealer. He admits he had a knife with no lawful purpose."

He added: "Why is the defendant carrying the knife? It must be in case something happens that forces him to use it whilst carrying out his trade." The court heard that the defendant said the men wanted to check the drugs before they bought them.

Mr Elliott said that the fight, which took place outside the Santander Bank, started with Mr Price throwing punches at Mr Wilson.

Although he initially tried to pull Mr Wilson away from his friend, Mr Ferreira also started to punch him, the court heard. During this time, the defendant stabbed Mr Ferreira.

The barrister said that after the stabbing, the defendant ran after his victim, across Epsom High Street, with the knife.

The court was told that Mr Wilson was apprehended by police community support officers, before running off again and being caught by members of the public.

Mr Elliott told the jury: "Having heard all the evidence in this case it will be a matter of fact for you whether this was a drug deal that got out of hand or, as the defendant will say, a robbery - that these two men robbed him of his produce.

"Either way, the Crown will say there was no need to use that knife.

"You may consider he went beyond self-defence and that by using the knife and thrusting it into someone else he intended to cause a serious wound."

Mr Wilson has already pleaded guilty to possessing five bags of cannabis, worth £50, with the intent to supply; and possessing a knife in relation to the same incident - offences of which the jury were informed.